Estimation of groundwater recharge and its relation to land degradation: case study of a semi-arid river basin in Iran

Abstract

Groundwater extraction is one of the most important criteria of land degradation especially land subsidence in arid and semi-arid areas. Understanding the relationship between water extraction and recharge of groundwater can lead to better watershed management. For the estimation of groundwater recharge in Razan-Ghahavand watershed in Central Iran the Soil and Water Assessment Tools was used. Model calibration was done by using SUFI-2 based on monthly river discharge and annual crop yield, where crop yield was used to better estimate the evapotranspiration term, which consequently increased our knowledge on estimating aquifer recharge. The calibration results were satisfactory: The Nash-Sutcliffe model efficiency ranged from 0.53 to 0.63 for calibration and from 0.42 to 0.72 for validation. The results showed that, although the groundwater level was decreasing about 1 m per year, the groundwater recharge did not change significantly leading to a net withdrawal causing land subsidence over time.

Spatially distributed impacts of climate change and groundwater demand on the water resources in a wadi system

“…SWAT is a semi-distributed model which is most commonly applied to simulate water fluxes on the catchment scale with diverse agricultural management options and under various hydrologic conditions over long periods of time (Arnold et al, 2012). As a process-based hydrological model, SWAT has proven its capability for climate change impact studies (Emami and Koch, 2019;Tigabu et al, 2021). The SWAT model of the Halilrood Basin is divided into 285 sub-basins and 6091 hydrologic response units (HRUs), defined by land use (FAO, 2009), slope, and soil type (ESA, 2010).…”

Hydrological Modeling and Runoff Mitigation in an Ungauged Basin of Central Vietnam Using SWAT Model

“…The water in each HRU can be stored in four levels: snow, soil profile (0-2 m), shallow aquifer (0-2 m) and deep aquifer (2-20 m). Rafiei Emam et al [15] revealed that a single HRU could not show the characteristics of a sub-basin. Therefore, we used multiple HRUs for sub-basin analysis in this research.…”

“…We calibrated a crop yield because calibration using a crop yield gives more confidence on actual evapotranspiration, and hence give the precise estimation of other water components such as, soil moisture, surface runoff and percolation [15]. The SUFI-2 algorithm was used to calibrate the crop parameters and uncertainty analysis.…”

“…The calibration based on crop makes the model results more confident [15]. There is a direct relationship between crop yield and evapotranspiration; therefore, the calibration of the model based on yield improves the simulation of other water components.…”